The leader of the British National party, Nick Griffin, told a crowd that white society had turned into a multiracial hell hole, a court heard today.

Mr Griffin claimed that Asian Muslims were trying to conquer the UK, Leeds crown court heard. In a videotape shown to the court, the BNP leader described Islam as a "wicked, vicious faith".

He also allegedly said in one speech that young Asian men were "seducing and raping white girls in this town right now".

The 45-year-old BNP leader and fellow party activist Mark Collett, 24, face a series of race hate charges.

The charges relate to six speeches the two men made last year in towns in West Yorkshire which were covertly filmed by an undercover BBC reporter.

Opening the prosecution's case, Rodney Jameson QC said that both of the accused had tried to win BNP votes by creating a "nightmare vision" of Asians carrying out attacks on white people.

Mr Jameson said: "The prosecution allege that each of the six speeches ... included words which were threatening, abusive and insulting towards, in particular, people of Asian ethnicity. Such words were used with the intention of stirring up racial hatred."

The jury heard that both men had addressed a crowd at the Reservoir Tavern in Keighley on January 19 2004.

The QC said Mr Griffin read statistics to the crowd which said that the white population of Bradford was just 1%, and that it was statistically 0% in Keighley.

In the videotape shown to the jury, Mr Griffin makes a range of accusations about gangs of Muslims involved in a "rape wave" in the West Yorkshire town.

He bemoans what he sees as the lack of police and government action, adding: "Now that sentence could get me seven years in prison."

He goes on: "If they get a non-Muslim girl and they get her pregnant, then her community doesn't want her, and the child generally grows up a Muslim and that's the way this wicked, vicious faith has expanded from a handful of cranky lunatics about 1,300 years ago to it's now sweeping country after country before it, all over the world."

Reading excerpts from the speeches, Mr Jameson said Mr Griffin said white society had turned into a multiracial hell-hole and urged the crowd to vote BNP in order to ensure "the British people really realise the evil of what these people have done to our country".

Referring to a recent attack in the area, Mr Jameson said Mr Griffin said: "The bastards that are in that gang, they are in prison so the public think it's all over. Well it's not. Because there's more of them.

"The police force and elected governors haven't done a damn thing about it. Their good book [the Koran] tells them that that's acceptable. If you doubt it, go and buy a copy and you will find verse after verse and you can take any woman you want as long as it's not Muslim women."

Mr Jameson said Mr Griffin's speech then turned to allegations of violence by Asian Muslims against whites. The QC said Mr Griffin said: "These 18, 19, and 25-year-old Asian Muslims are seducing and raping white girls in this town right now."

The court heard Mr Collett addressed the gathering on the same evening. Mr Collett allegedly said: "Let's show these ethnics the door in 2004."

During the speech, Mr Collett allegedly said: "In the space of a week there's always at least two rapes of girls, white girls between the ages of 15 and 16, by gangs of Asians."

In another speech on March 10 2004 at a pub in Pudsey, Leeds, Mr Collett allegedly claimed that young Muslim boys were being trained to use AK47s and Asians were "spilling out" from Bradford to Leeds, "because of the rate they breed".

Mr Jameson said the defendants used the technique of building fear and resentment of Asian people by referring to rapes and muggings.

Mr Jameson said that some of Mr Griffin's remarks may be thought of by some as "perfectly legitimate political comment". But the barrister added: "No society can permit disapproval of another race to be expressed in such strong terms that hatred be stirred up against people on the basis of race or ethnicity."

The QC insisted that the case was not about restricting freedom of expression and said the UK's laws in this area were "hardly onerous".

Mr Jameson told the jury of eight men and four women that BBC reporter Jason Gwynne obtained footage of the speeches after he joined the BNP in Bradford in December 2003.

He spent six months attending meetings and other events.

Mr Jameson said that West Yorkshire police began an investigation into the contents of the documentary the day after it was broadcast on July 15 2004.

Mr Griffin faces two charges of using words intended to stir up racial hatred and two alternative charges of using words likely to stir up racial hatred. Mr Collett faces four charges of the first offence and four of the alternative.

Mr Griffin, of Llanerfyl, Powys, and Mr Collett, of Rothley, Leicestershire, both deny the charges.

Yesterday some 600 rival protesters massed outside the courthouse; today there were only a handful of protesters.